Eternal Sunshine of the Spotless Mind: Scientists Discover How to Enhance and Suppress Memories with Uncanny Accuracy

Thursday, 23 May 2019 - 12:39PM
Medical Tech
Thursday, 23 May 2019 - 12:39PM
Eternal Sunshine of the Spotless Mind: Scientists Discover How to Enhance and Suppress Memories with Uncanny Accuracy
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Photos courtesy of The Ramirez Group, Boston University
Memory's fragility has played on our collective imagination in scores of books and movies – and neuroscientists have just discovered that it's possible to edit your memories by manipulating the brain's hippocampus. The findings were published in a new paper in Current Biology.


The hippocampus is part of the limbic system, a collection of structures deep within the brain that includes the amygdala and hypothalamus. Together, these structures form the epicenter of memory, learning, emotion, and behavior. The hippocampus is primarily concerned with long-term memory and location or spatial memory, along with the emotional response to both.


The study has its roots in the labs at MIT, where Dr. Steve Ramirez (senior author of the paper) and first author Briana Chen performed the initial research that would inform this cutting-edge discovery. Ramirez is now an assistant professor at Boston University where he specializes in neuroscience, psychology, and memory; Chen is a graduate researcher studying depression at Columbia University.


Although scientists already knew that the hippocampus stores our memories, where exactly do they live within the structure? And are different types of memories stored in different areas of the hippocampus? To find out, Chen and Ramirez monitored the neural response in male mice when they made new memories of experiences both positive and negative (for example: seeing a female mouse versus, say, experiencing a mild electrical shock).


The researchers used light-sensitive proteins that would glow when certain cells were activated within the brain, which revealed that different parts of the hippocampus performed very different roles indeed: negative memories live in the lower regions of the hippocampus, while more positive memories are stored up top. Chen and Ramirez used laser light to re-trigger these memories later on by activating different clusters of cells. Take a look:



Then something interesting happened: they noticed that stimulating the bottom of the hippocampus could actually induce long-term anxious behavioral changes in mice, not unlike the cause and effect of PTSD. "A lot of psychiatric disorders are based on the idea that after there's a really traumatic experience, the person isn't able to move on because they recall their fear over and over again," explains Chen.


Conversely, activating the top portion of the hippocampus could actually suppress these negative memories, blunting the trauma and reducing the intrusive thoughts and memories that trigger anxious behavioral changes over time.


The team is quick to point out that there are distinct differences between mouse and human brains, but discovering this principle in the first place is a huge leap forward in mapping human memory and understanding psychiatric disorders. Applying these principles could even allow us to one day dial memories up or down like an emotional sound mixer.


"The field of memory manipulation is still young… it sounds like sci-fi but this study is a sneak preview of what's to come in terms of our abilities to artificially enhance or suppress memories," observes Ramirez.


Photos courtesy of The Ramirez Group, Boston University
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